Heating apparatus



Sept. 21, 1943. F. R. HIGLEY HEATING APPARATUS Filed Feb. 9, 1940 3Sheets-Shea?I 1 INVENTOR.

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fAwK Mau Y Sept. 21, 1943. l F. R. HIGLEY HEATING APPARATUS Filed Feb.9, 1940 3 Sheets-Sheet 3 INVENT OR. En/VK E. //amsr ATTORNEYS PatentedSept. 21, 1943 HEATING APPARATUS Frank R. Higley, Cleveland Heights,Ohio, assignor to The Bryant Heater Company, Cleveland, Ohio, acorporation of Ohio Application February 9, 1940, Serial N0. 318,147(ClflZ-f-l'l) I 8 Claims.

This invention relates to improvements in heating apparatus, moreparticularly heating apparatus embodying an air blower, and applyingprimarily to warm air heating systems.

It is well known in the art that heat transfer from one space, such as acombustion chamber, to another space containing air to be heated, by wayof an intervening metal wall, is dependent largely upon two basicconditions: rst, the thermal conductivity of the Wall itself and second,the velocities of the gases contacting the opposite faces of the wall.Generally, it is the object of this invention to provide a constructionutilizing ametal wall of such character and gases moving at velocitiessuch as to function-most eilectively point of the wall metal even thoughthe temperature of the gases on its hot side may exceed the meltingpoint of the metal.

With these principles in view the invention contemplates the employmentof aluminum or the like as the wall material, disposing the wall as thescroll portion of the housing of a centrifugal blower, so that theradially inward surface of the wall will be wiped throughout its area bythe air discharged by the blower wheel, which of course is the air to beheated, the wiping being at maximum air velocity for the entire systemof which the apparatus of this invention constitutes the heating unit.

Still more particularly, and of equal importance, the inventioncontemplates the employment, for the scroll or heat transmitting wall;of an extruded section of aluminum or the like. Such section hassubstantial' advantage over anything heretofore employed in the art. Itprovides absolute uniformity of section, surfaces on both sides whichare perfectly smooth in one direction, that is longitudinally of thescroll, and yet permits complete latitude of deformation in the otherdirection, thereby lending itself to the formation of longitudinal fins.It promptly oxidizes on its hot surface under exposure to combustiongases but without other depreciation to form a thin nlm of relativelylow conductivity whereby peak temperatures at isolated locations areavoided and the metal itself is protected against the action of acid inthe combustion gases; and, on the cooler side its smooth surface notonly offers minimum resistance to wiping flow of air thereover, butremains relatively bright so as to minimize radiant heat loss, which hassome importance as will appear. Furthermore, a scroll formed of anextruded section permits of a novel and superior arrangement of mountingbetween the side plates of the blower housing, which manner of mountingpermits some relative freedom for expansion adjustment circumferentiallyof the scroll while positively maintaining the scroll xed in radialdirection.

It will be observed that the extruded scroll has such curvature in onedirection and is so fixed along its curved edges with the side platesbetween Wl'iich it is disposed, that there is provided maximumresistance to buckling under temperature differences of either thescroll or side plates.

The invention further contemplates employ-- ment not only4 of the heatconducting scroll described, but also 0f a second heat transferring wallradially outward from the scroll, so that a nue passage for products ofcombustion is formed bounded radially between these two walls andlongitudinally of the blower axis by the two side plates. Still further,the invention contemplates -employment of the same section of the samematerial for these two walls .so that under conditions of expansion andcontraction the two blower housing side plates are positivelymaintained, in parallel relation with each other, against buckling.

Still further, the invention contemplates employment of facecharacteristics for the extruded section, such that there will bemoreeffective surface area' on one face of the section than on the other,and consequently capacity for more rapid heat transfer on one face thanon the other. The dispositionof the extruded section to present the faceof larger effective area either toward or away from the blower wheeldepends upon the rquirements of the particular design. If, for example,the heat applied to the hot side of the scroll is not too great and theair ilow on the cool side is relatively rapid, the greater surface areashould be on the side remote from the blower wheel. As the heat appliedto the hot side increases however, or the rate 0f air flow on the coolside decreases, the difference in surface areas lon the two sides of thescroll should become less and less. Under certain conditions theeffective surfaces may be equal. Finally, if the heat on the hot sidebecomes great enough or the air flow rate on the cool side becomes lowenough a reversal of the relative areas herein illustrated will benecessary, in other words the extruded section should then be sodisposed as to direct the surface of larger effective area toward theblower wheel.

One of the objects of the invention therefore is the provision of heatexchange apparatus of compact form and high efficiency.

Another object is the provision of heating apparatus in which aluminumor other non-ferrous metal of high thermal conductivity and relativelylow melting point may be employed as the heat transfer wall.

Another'object of the invention is the utilization of the scroll of theblower as the heat exchange wall of a furnace, and the formation of thatscroll of aluminum so constituted as to facilitate the wiping of the airfilm from the scroll wall by the action of the blower.

Another object of the invention is the formation of the scroll ofextruded aluminum, suitably ribbed for strength and increased surface.

A further object is the provision of novel means for interconnecting thescroll and the side plates of the blower.

Other objects and -features of novelty will appear as I proceed with thedescription of those embodiments of the invention which, for thepurposes of the present application, I have illustrated in theaccompanying drawings, in which Fig. 1 is a diagrammatic' side view,partly in section, of a warm air furnace embodying the invention,

Fig. 2 is a transverse sectional view taken substantially on. the line2|2 of Fig. 1.

Fig. 3 is a 'detail sectional view on a larger scale showing a sectionof extruded aluminum scroll wall.

Figs. 4 and 5 are views similar to Figs. 1 and 2, illustrating a.modified form of the invention.

Figs. 6 and 7 are similar views of still another modication of theinvention. t

Fig. 8 is a detail perspective view partly in section illustrating onemeans for attaching the scroll to a side plate of the blower.

Fig. 9 is a detail view of the scroll with a modied form of groove alongits edge adapted to accommodate bolts as fastenings.

Figs. 10 and 1l are fragmental views at right angles to each otherillustrating a bolt with a fIatted head adapted to be used with thescroll of Fig. 9.

Fig. l2 is a detail view of a modified form of scroll wall.

In Figs. l and 2 of the drawings the casing of a warm air furnace isindicated at I0. The intake for cold air is shown at |I and the outletfor heated air at I2. Air lters I3 may be em- -ployed if desired,through which the air must pass before entering the furnace proper.Within the casing and spaced from the side walls thereof I mount ablower wheel I4 of conventional design comprising a shaft I5 upon whichis mounted a pulley I6 driven by a belt I'I from an electric motor I8,over which there is a guard I8' to protect it from the heat. I'he fan isenclosed partially by a scroll |9 which terminates at or is connectedwith the warm air outlet I2. l

The scroll I9, which may be of a width somewhere between six inches andtwelve inches, is attached at its edges to blower side-plates 29 and 2|which preferably extend down to the base of the casing. Angle bars 22upon which the bearings for shaft I5 are carried may be attached tothese side plates.

The blower assemblyl includes a conductor or flue/23 for hot gases, theinner wall of which is constituted by the scroll I9 and the side wallsby the side plates 20 and 2| of the blower. The remaining or outer wall24 is secured between the side plates 20 and 2| and is curved throughoutat least a portion of its length'so as to confine the hot gases to apath adjacent the scroll I9. The lower end of this outer wall howeverextends down to the base of the casing, forming with the lower part ofscroll I9, the side plates of the blower and the bottom and one end ofcasing I0, a combustion chamber 25 in which is located a burner 26. Anintake for air to support combustion is provided at 21. A suitable vent29 is provided at the opposite end of the conductor 23 with which a pipe29 leading to a chimney is connected.

'I'he two strips from which the scroll I9 and wall 24 are built arepreferably identical in cross section and made of the same non-ferrousmetal, although this is not necessarily the case. The scroll I9 isobviously the more vital element of the invention, and the wall 24 couldbe a strip of ordinary ferrous sheet metal if for reasons of economy infirst cost it should appear desirable o to make it so. However, linaccordance with the preferred form of the invention, not only the scrollI9 but also the wall 24 are made of anV extruded aluminum strip curvedto the desired form. As illustrated in Fig. 3 this strip may haverelatively high ribs 30 on one side and lower ribs 3| en the other side,the ribs of one surface lying opposite the grooves of the other surface.The latter arrangement has the advantage that expansion and contractiondue to temperature changes tends to be localized in the individualcorrugations of the strip-rather than to cause bowing of the strip as awhole in a transverse direction. The ribs also strengthen the strip inthe manner of corrugations in sheet metal. A further function of theribs however is to increase the surface exposed to the air currents onone side of the strip and to the hot gases on the other side thereof,thereby increasingthe rate of heat transfer, the height of the ribsbeing proportioned to fit the requirements of the case.

In the embodiment illustrated I arrange the extruded strip for scroll I9so as to present the high ribs 30 on the outer side and the lower ribs3| on the inner side. The high ribs, having large surfaces, absorb heatrapidly. On the inner side of scroll I9 the ribs present relatively lesssurface because it is assumed that the air flowing over these ribs ismoving very rapidly and is capable of removing heat therefrom at leastas rapidly as it can accumulate therein.

In the case ofthe wall 24 the high ribs 30 are arranged externally,considered with respect to the conductor 23 through which the hot gasesow. In the illustrated embodiment air in contact with the outer surfaceof the wall is moving slowly under the suction drag of the blower,instead of rapidly as in the discharge from the blower. `On the innerside of the wall facing the hot gases in conductor 23 those gases impartheat to the wall. It should not absorb heat as readily as its outersurface gives olf heat to -the slowly moving air, because of course itis desirable that the temperature of the wall be prevented fromapproaching too closely the melting point of the metal used in itsconstruction, Hence I arrange the high ribs on the outer surface and thelower ribs on the inner surface.

In the modication illustrated in Figs. 4 and 5 the construction of thefurnace is like that of Figs. 1 and 2 in most essential particulars. Theair to be heatedenters the casing 35l at 36, passes through filters 31and around the blower side plates 38 into the ends of the hollow wheel39, being discharged from the wheel centrifugally against a scroll 40and being delivered through outlet 4I. Products of combustion rise fromburner 42 and iiow upwardly on one side of scroll 40 between that scrolland an 'outer wall 43 and out through stack 44. extruded aluminum andwall 43 is also preferably formed of the same material. A part of thehot gases also flow upwardly along the other side of scroll 40 betweenthat scroll and a transverse sheet metal wall 45 interposed' between thetwo side plates 38. This part of the conductor for hot gases lsconnected by means of one or more small pipes 46 with stack 44, the pipeorpipes 46 extending through the air delivery part of the blower.

Still another ymodified form of furnace is illustrated in Figs. 6 and 7,this type being designed primarily to be placed upon the oor of abasement, whereas the two previously described embodiments arepreferably attached to the ceiling of a basement or other room.- In thepresent embodiment the return air flows downwardly at 50 into thefurnace casing 5I, through an air filter 52, around side plates 53 ofthe blower into the ends of the hollow wheel 54, from which it isdischarged centrifugally and passes out through the upwardly directedexit 55. A scroll 56, preferably of extruded aluminum, is used. Part ofthe hot gases from burner l liiows upwardly between scroll 56 and anouter wall 58, also made preferably of extruded aluminum. 'Ihe rest ofthe gases `iiow upwardly on the opposite side of scroll 56 between thatscroll and a sheet metal guard 59 interposed between the side plates 53of the blower, the gases traveling thence through one or more horizontalpipes 60 into the upper end of the space between scroll 56 and wall 58,all of the gases leaving by way of exit 6l and stack 62.

As illustrated in Fig. 3 I may provide grooves 65 in the two side edgesof the extruded metal strips forming the radially separated walls of theflue. The width of these grooves is such that screws of a given diameterwhen driven through holes in the blower side plates will enter thegrooves and form their own threads in the relatively soft metal of thestrips, thereby effectively connecting the strips. and the side plates.As a modification of this type of fastening I may provide small ribs orteeth 66 facing inwardly from the walls of the grooves, see Fig. 8, theteeth on one side of the groove being staggered with respect to those onthe opposite side and so placed that screws 61 with a properlyproportioned thread will engage the teeth on the two sides of thegroove, the teeth thereby taking the place of ordinary threaded sockets.The teeth are formed of course in the extruding operation.

In Fig. 9 I have illustrated still another form of edge groove 68 havinga constricted mouth 69 of a width just suiilcient to accommodate theatted head 'I0 of a bolt 1|. Such bolts can be inserted through holes inthe side plates of the blower, and when the heads are within the groovebeyond the constricted mouth 69 they may be' `Scroll 40 is formed ofturned through an angle of whereupon they are locked in place. Thefastening is then completed by screwingnuts onto the exposed ends of thebolts.

In Fig. 12 is shown one modification of an extruded metal strip that maybe employed, this strip having ribs 12 on one side and a flat surface T3on the opposite side. When this strip is used for the scroll member thesmooth surface is directed inwardly, assuming that the other factors ofdesign are the same as in the embodiment herein disclosed. The smoothsurface is also directed inwardly when used for the outer Wall. The ribsin each case therefore are on the outer side just as the higher ribs areon the outer side in the scroll and wall previously described, it beingthe purpose in all instances in which a blower is involved to providemore rapid transfer-of heat from the flue through the inner wall thereofthan through the outer wall.

While in the drawings I have shown the scroll l section, it will beappreciated that the lengthy of such extruded section in one or both ofthese walls may be decreased if desired, the balance of the walls beingconstructed of sheet metal or other relatively low cost material. Suchshort extruded sections of course call for a relatively high degree ofheating in order to maintain the desired efficiency of the apparatus.

In each of the modifications illustrated the air intake is so arrangedthat upon entering the casing the air is directed against the hottestportions of the outer wall 24, 43 or 58, as the case may be, this beinga matter of primary importance where such outer wall is formed of metalof low melting point, as is preferred..

Having thus describedvmy invention, I claim:

1. In apparatus of the character described, a volute heat exchanger wallformed of extruded aluminum having integral longitudinal fins.

2. In heating apparatus, a volute wall formed of extruded aluminumhaving integral longitudinal ns on at least one surface thereof, andmeans for conducting combustion gases over the outer surface of thevolute wall in a direction longitudinally thereof.

3. In heating apparatus, a blower wheel adapted to receive air to beheated axially and deliver it centrifugally,'a scroll for said wheel,means for heating said scroll externally, said scroll being formed ofextruded aluminum having longitudinal grooves Yin its edges, ferrousmetal side plates, and fastenings extending through said side platesinto said grooves for holding the scroll in assembled relation with `theside plates.

4. In heating apparatus, a blower wheel adapted to receive air to beheated axially and deliver it centrifugally, a scroll for said wheel,means for heating said scroll externally, said scroll being formed ofextruded aluminum, said scroll having longitudinal grooves in its edges,ferrous metal side plates, and screws extending through said side platesinto said grooves, the diameter of the screws being greater than thewidth of the. grooves whereby the screws form their own threads in thescroll.

5. In heating apparatus, a blower wheel adapted to receive air to beheated axially and deliver it centrifugally, a scroll for said wheel,means for heating said scroll externally, said scroll being formed ofextruded aluminum, said scroll having longitudinal grooves in its edges,small teeth running along the sides oi the grooves.'

ferrous metal side plates, and screwsextending through said side platesinto said grooves, the

threads of the screws engaging said teeth in the manner oi' screwsengaging threaded openings. Y

6. In heating apparatus, a blower wheel adapted to receive air to beheated axially and deliver it centrifugally, a scroll for said Wheel,means for heating said scroll externally, said scroll being formed ofextruded aluminum, said scroll l fastenings between said side wallmembers and the edges of said volute and outer walls and the said sideWall members permitting elongation, of the volute and outer wall, saidside wall members extending across the edges of said volute and one ofthem having an opening for admitting air to the apparatus, means forcausing products oi combustion to pass between the volute and outerwalls, and a blower wheel within the volute wall, whereby air is causedto ow at high speed over the inner surface of said volute and out of theapparatus.

8. In heating apparatus. a volute wall. an outer Wall partiallyencircling said volute wall, both of said volute and outer walls beingformed of high heat conducting, high expansion metal, high strengthmetal side plates joined ,to the side edges of said volute and outerwalls to provide therebetween a conductor for combustion gases, saidvolute and outer walls having longitudinal grooves in their edges andsaid side walls having fastenings extending into said grooves permittingexpansion and contraction -of the volute and outer walls lengthwise.

FRANK R. HIGLEY.

